ELEANOR HALL: It's 45 years since the Commonwealth government closed the Rum Jungle uranium mine, and traditional owners are asking why the site still has not been cleaned up.

The mine, 100 kilometres south of Darwin, was a Commonwealth-backed venture that produced uranium for the nuclear weapons programs of the US and British governments.

In this month's budget, the Government allocated $11 million to put the finishing touches on a plan for rehabilitation.

But putting the plan in place is likely to cost much more than that, as Sara Everingham reports.

SARA EVERINGHAM: Traditional owner Kathy Mills finds every visit to site of the old Rum Jungle uranium mine upsetting.

It's overrun with scrubby weeds, there are two abandoned mining pits, large mounds of waste rock, and the water in a diverted channel of the Finniss River is tinged an orange-brown from contamination.

But the great-grandmother is showing me around in the hope it'll help with her family's long battle to have the site rehabilitated.

KATHY MILLS: And it has just been lingering on and on and on. Many of my people have passed on and I am almost the last man standing in the people who fought for recognition of this land.

SARA EVERINGHAM: Kathy Mills vividly remembers the anger of one of her older relatives when he saw for the first time how the mine had transformed the land.

One of the mining pits was dug into a sacred women's site on the east branch of the Finniss River. The flow of the river was diverted for one kilometre. Traditional owners were given no say in it.

KATHY MILLS: It took away the whole aspect of the importance of that land.

SARA EVERINGHAM: But when the mine was developed in the early 1950s, the Commonwealth saw uranium as an opportunity to develop the north.

The United States and Britain were on the hunt for the mineral, and as one of Australia's first uranium mines, Rum Jungle was developed to supply the nuclear weapons programs of the US and British Governments.

Robert Menzies came to the Top End to open it.

OLD NEWSREEL AUDIO: The Prime Minister opened the Rum Jungle uranium mine.

Rum Jungle - where a great new treatment plant for uranium ore is producing raw material for worldwide atomic research bringing unprecedented prosperity to the hitherto lonely north.

SARA EVERINGHAM: The mine closed in 1971, but it remains off limits to the public, and the site had to be left out of a successful land claim in the Finniss River region to protect traditional owners from becoming liable for the environmental cleanup.

(Water running and bubbling)

Today staff from the Northern Territory Mines Department are at the site monitoring the water in the Finiss River.

TANIA LAURENCONT: You see elevated concentrations of metals and sulphate going down the river and causing impacts downstream.

SARA EVERINGHAM: When mining finished at Rum Jungle, no rehabilitation was done and the site became notorious for its environmental problems.

The Commonwealth spent $18 million on rehab in the ‘80s, but some of the work didn't last.

Tanya Laurencont says the biggest problem is not radiological waste, but acid and metals leaching from waste rock into the environment.

TANIA LAURENCONT: What we're seeking to do now is to really find a long term sustainable solution for the site.

SARA EVERINGHAM: Since 2009, the federal government has spent another $18 million on a new rehabilitation plan for Rum Jungle.

The recent federal budget had $11 million for the Northern Territory Government to continue monitoring and to finish drawing up the cleanup plan.

The mines department estimates it'll take another eight years to rollout that cleanup plan at a cost of more than $200 million.

But the head of the Northern Territory Government's Legacy Mines Unit, Mike Fawcett, says not doing the work would also have costs.

MIKE FAWCETT: We've seen, starting to see a deterioration in quality at the site. That will continue to gradually degrade and potentially if we get cyclonic events, that may be a catastrophic step of degradation, so the impacts in the river system will increase over time again.

SARA EVERINGHAM: Mining scientist Tania Laurencont says the cleanup plan could involve putting the diverted section of the Finniss River back on its natural course.

TANIA LAURENCONT: We're talking to traditional owners for this area, and they were really excluded not just during mining phase but during the ‘80s rehab, and so we've started a discussion with them several years ago to identify what they would find as a sustainable long term site.

Also it’s really - from an environmental perspective really knowing more now, so in terms of leading practice for mine rehabilitation. Since the ‘80s we’ve learnt an awful lot, and what we’re looking at is implementing those types of practises so that we just can keep on improving the environmental situation here.

Traditional owner Kathy Mills says she hopes the land will be cleaned up and handed back to Aboriginal people within her lifetime.

KATH MILLS: I am feeling hopeful and I am hoping that I am feeling right because time is running out for me as well and it's been a long haul trying to get some action to rehabilitate.

SARA EVERINGHAM: The Federal Government says any future funding for Rum Jungle will be worked out once the Northern Territory Government finishes its rehabilitation plan.